Mineral Resources of the Ferris Mountains Wilderness Study Area, Carbon County, Wyoming &£ %r^ U.S. GEOLOGICAL SURVEY BULLETIN 1757-C .r WYOMING Chapter C Mineral Resources of the Ferris Mountains Wilderness Study Area, Carbon County, Wyoming By MITCHELL W. REYNOLDS U.S. Geological Survey JOHN T. NEUBERT U.S. Bureau of Mines U.S. GEOLOGICAL SURVEY BULLETIN 1757 MINERAL RESOURCES OF WILDERNESS STUDY AREAS- SOUTHERN WYOMING DEPARTMENT OF THE INTERIOR DONALD PAUL MODEL, Secretary U. S. GEOLOGICAL SURVEY Dallas L. Peck, Director UNITED STATES GOVERNMENT PRINTING OFFICE: 1988 For sale by the Books and Open-File Reports Section U.S. Geological Survey Federal Center Box 25425 Denver, CO 80225 Library of Congress Cataloging-in-Publication Data Reynolds, Mitchell W. Mineral resources of the Ferris Mountains Wilderness Study Area, Carbon County, Wyoming. (Mineral resources of wilderness study areas southern Wyoming ; ch. C) (U.S. Geological Survey bulletin ; 1757-C) Bibliography: p. Supt. of Docs, no.: I 19.3:1757-C 1. Mines and mineral resources Wyoming Ferris Mountains Wilderness. 2. Ferris Mountains Wilderness (Wyo.) I. Neubert, John T. II. Series. III. Series: U.S. Geological Survey bulletin ; 1757-C. QE75.B9 no. 1757-C 557.3 s [553'.09787'86] 87-600485 [TN24.W8] STUDIES RELATED TO WILDERNESS Bureau of Land Management Wilderness Study Areas The Federal Land Policy and Management Act (Public Law 94-579, October 21, 1976) requires the U.S. Geological Survey and the U.S. Bureau of Mines to conduct mineral surveys on certain areas to determine the mineral values, if any, that may be present. Results must be made available to the public and be submitted to the President and the Congress. This report presents the results of a mineral survey of the Ferris Mountains Wilderness Study Area (WY-030-407), Carbon County, Wyoming. CONTENTS Abstract Cl Summary Cl Character and setting Cl Mineral occurrences C3 Mineral resource potential C3 Introduction C3 Area description C3 Previous and present investigations C5 Appraisal of identified resources C6 History and production C6 Mineral occurrences C6 Assessment of potential for undiscovered resources C7 Geology C7 Late Archean and older crystalline rocks C7 Mesozoic and Paleozoic sedimentary rocks C8 Tertiary sedimentary rocks C8 Quaternary surficial deposits C8 Structure C9 Geochemistry C12 Geophysics C12 Mineral and energy resource potential C14 Metallic minerals C14 Nonmetallic minerals C15 Energy minerals C15 Oil and natural gas C16 References cited C17 Appendix C19 PLATE [Plate is in pocket] 1. Map showing mineral resource potential, geology, and prospects of the Ferris Mountains Wilderness Study Area FIGURES 1. Index map showing location of the Ferris Mountains Wilderness Study Area C2 2. Summary map showing mineral resource potential and generalized geology of the Ferris Mountains Wilderness Study Area C4 3. Map showing complete Bouguer gravity anomalies of the Ferris Mountains Wilderness Study Area and adjacent areas C13 Contents TABLE 1. Sequence of stratigraphic units in the Ferris Mountains Wilderness Study Area and their regional significance for mineral and fossil-fuel occurrences CIO VI Contents MINERAL RESOURCES OF WILDERNESS STUDY AREAS-SOUTHERN WYOMING Mineral Resources of the Ferris Mountains Wilderness Study Area, Carbon County, Wyoming By Mitchell W. Reynolds U.S. Geological Survey John T. Neubert U.S. Bureau of Mines ABSTRACT certainty level of D, for undiscovered phosphate, gypsum, uranium and thorium, coal, and oil and gas. The Ferris Mountains Wilderness Study Area (WY-03CM07) encompasses most of the Ferris Mountains in SUMMARY south-central Wyoming. It contains 20,495 acres across the narrow, rugged mountain range. Field investigations of the Character and Setting mineral resources of the area were conducted during 1983 and 1984. Mineral exploration, which began in 1870 and has The Ferris Mountains Wilderness Study Area is in been intermittent since, concentrated on the Babbs mine and south-central Wyoming (fig. 1) about 35 mi (miles) north of Spanish mine areas and on numerous small sites at which Rawlins and 65 mi west of Casper. The area contains about very low grade occurrences of silver, copper, lead, zinc, and 20,495 acres in the Ferris Mountains, a narrow rugged gold had been identified. During the present study, all mountain range where 9,400- to 10,037-ft-high peaks rise workings were examined and representative rock and above adjacent dissected rolling terrain. Unimproved ranch mineral samples from them were analyzed. Reconnaissance roads lead to the base of the mountains, but access within geochemical sampling of rocks, minerals, and stream the mountains is only by foot. Archean (see geologic time sediments was conducted for the entire area. Low, but chart in appendix) granite and granodiorite, which contain anomalous concentrations of silver, copper, arsenic, and lenses of older metasedimentary and metavolcanic rock and locally gold, lead, and zinc were identified in rock and mineral are intruded by linear dikes of basalt and diorite, support the samples from areas of the workings and at three other sites northern and southwestern parts of the mountains. within the study area. Small isolated occurrences of copper Sedimentary rocks of Cambrian through Cretaceous age or silver in very low concentrations were identified at several unconformably overlie the Archean crystalline rocks (pi. 1 other localities. All metallic mineral occurrences are in quartz and table 1). All of the rocks along the north flank and east veins or narrow shear zones in dikes and in lenses of half of the area are folded monoclinally and dip south. All metamorphic rock in granite. There are no identified rocks in the southwestern part are folded anticlinally; a resources in the area. Crystalline rocks of the study area have shallow syncline that trends northwest diagonally across the low mineral resource potential, with a certainty level of C, for area separates the tilted and folded blocks. Strata on the all undiscovered metallic minerals including gold, silver, west and south flanks dip steeply into the adjacent copper, lead, zinc, iron, nickel, molybdenum, tungsten, structurally deep Camp Creek syncline (fig. 1). The steep lithium, beryllium, and manganese. Sedimentary rocks of the north flank of the range marks a zone of normal faults, study area have no resource potential for any metallic segments of which have moved during Quaternary time. elements, at certainty level D. Resource potential for Tertiary rocks on the north are faulted down relative to undiscovered calcium carbonate and silica is low, with a Archean crystalline and Paleozoic sedimentary rocks of the certainty level of C, and no resource potential exists, with a mountains on the south. Ferris Mountains Wilderness Study Area C1 107°30' 107°15' 42°30' NATRONA COUNTY CARBON COUNTY APPROXIMATE BOUNDARY OF FERRIS MOUNTAINS WILDERNESS STUDY AREA (WY-030-407) FREMONT COUNTY I 42°15' SWEETWATER COUNTY Mahoney Oil Field GREAT DIVIDE BASIN SEPARATION FLATS Figure 1. Index map showing location of the Ferris Mountains Wilderness Study Area, Carbon County, Wyo. Mineralized rock in Miners Canyon (pi. 1; fig. 2), at the INTRODUCTION east end of the study area, was prospected between 1870 and 1890. Small amounts of gold were reportedly milled from vein quartz prior to 1890. Intermittent, but poorly documented Area Description activity continued until the 1980's, when claims were filed and sampling programs were conducted in the Miners Canyon area. During the early 1950's, near the center of the The Ferris Mountains Wilderness Study Area wilderness study area, exploration was conducted at the (WY-030-407) was studied at the request of the U.S. Babbs mine (fig. 2; pi. 1). Open cuts and two shallow adits Bureau of Land Management (BLM); it contains were excavated to examine silver, copper, lead, and, rarely, approximately 20,495 acres in the Ferris Mountains, gold occurrences. The Babbs mine area has not been worked south-central Wyoming (figs. 1, 2). The area is about since. Numerous prospect pits have been excavated along 1.5-4 mi wide and 13.5 mi long, elongate in a general quartz veins, in ferruginous shear zones, and in inclusions of west-northwest direction parallel to the crest of the metamorphic rock in the widespread Late Archean granitoid Ferris Mountains. The narrow mountain range rises rocks of the area. abruptly from the broad valley of the Sweetwater River on the north and from Separation Flat on the south (fig. 1). From an elevation of about 9,100 ft near the east end of Mineral Occurrences the study area, the range crest rises to 10,037 ft at Ferris Mountain in the north-central part of the range (fig. 2; pi. Small occurrences of copper, lead, and silver, and trace 1). Near the center of the area, the mountain crest is amounts of gold exist in the Babbs mine (fig. 2) and Miners Canyon areas. Other isolated occurrences in the upper part of offset southwest across Youngs Pass, elevation 8,750 ft. Garden Creek drainage and on the mountain crest at the The southwest segment of the crest rises near Muddy head of Pete Creek contain small amounts of copper, silver, Creek to elevations of 9,350-9,670 ft and extends west- and zinc or lead. Concentrations of these metals are northwest to Black Canyon (fig. 2). Near Cherry Creek extremely low and limited in areal extent, and no identified the mountain crest of the eastern part of the range resources are present. declines in elevation progressively west to form a subordinate northwest-striking ridge north of the southwestern crest. Terrain is particularly steep on the Mineral Resource Potential south flank of the mountains where picturesque flatirons of white limestone and locally of pale-yellow sandstone Low anomalous concentrations of copper, silver, locally rise at very steep angles from adjacent rolling surfaces. gold, and zinc or lead are present at widely separated Permanent and intermittent streams drain north, localities in the Ferris Mountains Wilderness Study Area.